Vagus Nerve

Vagus Nerve

in man, the tenth pair of cranial nerves, a paired mixed nerve containing motor, sensory, and autonomic (sympathetic and parasympathetic) fibers. The vagus nerve has three nuclei in the medulla oblongata in common with the glossopharyngeal nerve—the dorsal nucleus (autonomic); the ventral, or ambiguus, nucleus (motor); and the nucleus of the so-called tractus solitarius (sensory). The sensory fibers of the vagus nerve originate in two ganglia (superior and inferior) situated outside the cranium in the region of the jugular foramen. They then enter the cranial cavity and proceed to the medulla oblongata, from which they emerge with the vagus nerve through the jugular foramen. The vagus nerve is located in the neck with the carotid artery and jugular vein. It penetrates to the thorax, from which, together with the esophagus, it passes through the diaphragm into the abdominal cavity, forming plexuses on the walls of the esophagus, stomach, and so on. The motor fibers of the vagus nerve supply the muscles of the larynx, pharynx, esophagus, stomach, intestines, blood vessels, and heart (inhibition of cardiac activity, regulation of blood pressure, and so forth). The sensory fibers of the vagus nerve supply the occipital portions of the dura mater, the neck organs, stomach, and lungs. The vagus nerve participates in many reflex acts (swallowing, coughing, vomiting, filling and emptying of the stomach) and in regulation of the heartbeat and breathing. It is also part of the solar plexus. Injury to the motor nuclei of the vagus nerve impairs swallowing, phona-tion, articulation, and respiration—that is, the so-called bulbar disturbances, which occur in bulbar paralysis, amyotrophic lateral sclerosis, myeloencephalitis, and other diseases.

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